Nearly 80% of Schizophrenia Risk Is Genetic

As much as 79% of schizophrenia risk could be attributed to genetic factors, according to results from the largest study of twins in schizophrenia research to date.

Previous research has shown that both genetic and environmental factors contribute to the risk of developing schizophrenia. In a recent study, researchers sought to update heritability estimates based on data from 31,524 twin pairs from 2 nationwide registers in Denmark.
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Overall, the probandwise concordance rate of schizophrenia was 33% in monozygotic twins and 7% in dizygotic twins, and the researchers estimated heritability of schizophrenia to be 79%. After expanding outcomes to include schizophrenia spectrum disorders, the heritability estimate was 73%.

“The key strength of this study is the application of a novel statistical method accounting for censoring in the follow-up period to a nationwide twin sample. The estimated 79% heritability of [schizophrenia] is congruent with previous reports and indicates a substantial genetic risk. The high genetic risk also applies to a broader phenotype of [schizophrenia] spectrum disorders. The low concordance rate of 33% in monozygotic twins demonstrates that illness vulnerability is not solely indicated by genetic factors,” the researchers concluded.

—Michael Potts

Hilker R, Helenius D, Fagerlund B, et al. Heritability of schizophrenia and schizophrenia spectrum based on the nationwide Danish twin register [published online August 30, 2017. Biol Psych. http://dx.doi.org/10.1016/j.biopsych.2017.08.017.